CN112665423A

CN112665423A - Plate heat exchanger

Info

Publication number: CN112665423A
Application number: CN202011003855.1A
Authority: CN
Inventors: 小野贵大
Original assignee: Rinnai Corp
Current assignee: Rinnai Corp
Priority date: 2019-10-15
Filing date: 2020-09-22
Publication date: 2021-04-16
Also published as: KR20210044681A; JP7382202B2; JP2021063615A; US20210108859A1

Abstract

The present invention provides a plate heat exchanger, wherein adjacent heat exchange bodies (10) are formed in a way that a projection surface (55) of a through hole (13) of one heat exchange body (10) is not overlapped with a through hole (13) of the other heat exchange body (10), and a plurality of heat exchange bodies (10) are provided with: a heat exchanger (P) having a varying section (17, 18) on a projection surface (55) where the height of a flow path of a first fluid varies; and a heat exchange body (Q) having a flat surface section (19) on the projection surface (55) where the height of the flow path of the first fluid is substantially constant, wherein at least the second heat exchange body (10b) adjacent to the downstream side of the most upstream heat exchange body (10a) located at the most upstream of the flow path of the second fluid is composed of the heat exchange body (Q).

Description

Plate heat exchanger

Technical Field

The present invention relates to a plate heat exchanger including a plurality of heat exchange bodies that exchange heat between a first fluid flowing inside and a second fluid flowing outside, the plate heat exchanger being configured by stacking the plurality of heat exchange bodies.

Background

A plate heat exchanger including a plurality of heat exchange bodies in which an upper heat exchange plate and a lower heat exchange plate are joined to each other has been proposed (for example, korean patent registration No. 10-1608149). Each heat exchange body has: an inner space through which a heating medium as a first fluid circulates between the upper heat exchange plate and the lower heat exchange plate; and a plurality of through holes that pass through the internal space in a non-communicating state and through which combustion exhaust gas as a second fluid flows in the vertical direction.

The plate heat exchanger is configured by stacking a plurality of blocks having at least one heat exchange body in the vertical direction. The blocks adjacent in the vertical direction communicate with each other so that the heat medium flows therethrough. Further, the adjacent blocks are configured such that the flow direction of the heat medium flowing through one block is different from the flow direction of the heat medium flowing through the other block. This makes the flow path of the heat medium flowing through the heat exchanger longer according to the number of layers of the block, thereby improving the thermal efficiency.

However, in the heat exchange body in which the through hole penetrates the internal space in a non-communicating state as described above, the peripheral edge portion of the through hole through which the combustion exhaust gas passes is heated most. Therefore, in order to improve the thermal efficiency, it is preferable to have a structure in which the heat of the combustion exhaust gas is efficiently thermally transferred to the heat medium at the peripheral edge portion of the through hole.

In the plate heat exchanger in which a plurality of heat exchange bodies are stacked, when the adjacent heat exchange bodies are formed such that the projection surface of the through hole of one heat exchange body does not overlap with the through hole of the other heat exchange body as viewed in the gas flow path direction of the combustion exhaust gas, the gas flow path of the combustion exhaust gas in the heat exchanger becomes long, and the thermal efficiency can be improved.

However, in the heat exchanger having the arrangement structure of the through holes as described above, the through hole of the heat exchange body on the upstream side is opposed to the projection surface of the heat exchange body on the downstream side on which the through hole is not formed. Therefore, the combustion exhaust gas flowing through the through hole of the heat exchanger on the upstream side first collides with the projection surface on one surface of the heat exchanger on the downstream side, then spreads on one surface of the heat exchanger on the downstream side, and further flows from the through hole of the heat exchanger on the downstream side to the downstream side of the gas flow path of the combustion exhaust gas. Therefore, in the upstream region of the gas flow path of the combustion exhaust gas through which the high-temperature combustion exhaust gas flows, a portion of the downstream-side heat exchanger body facing the through hole of the upstream-side heat exchanger body, that is, a projection surface of the downstream-side heat exchanger body is intensively heated, and thus, there is a problem that local heating occurs. In particular, the heat exchanger on the downstream side adjacent to the heat exchanger on the most upstream side in the gas flow path of the combustion exhaust gas does not exchange heat with the heat medium flowing through the heat exchanger on the most upstream side, but collides with the high-temperature combustion exhaust gas flowing through the through hole of the heat exchanger on the most upstream side. Therefore, local heating is likely to occur in the heat exchange body on the downstream side adjacent to the heat exchange body on the most upstream side.

Disclosure of Invention

The present invention has been made to solve the above problems, and an object of the present invention is to improve thermal efficiency and to prevent local heating of a heat exchanger in an upstream region of a flow path of a second fluid.

According to the present invention, there is provided,

provided is a plate heat exchanger comprising a plurality of heat exchange elements for exchanging heat between a first fluid flowing inside and a second fluid flowing outside, wherein the plate heat exchanger is configured by stacking the plurality of heat exchange elements,

the heat exchange body has a plurality of through-holes formed in such a manner that: causing the second fluid to flow outside the heat exchange body in a direction intersecting a flow path surface of the first fluid flowing inside the heat exchange body,

the adjoining heat exchange bodies are formed in the following manner: a projection plane of the through hole of one heat exchange body does not overlap with the through hole of the other heat exchange body as viewed from a flow path direction of the second fluid,

the plurality of heat exchangers includes: a heat exchanger (P) having a varying section on the projection surface, the varying section varying in height of the flow path of the first fluid; and a heat exchanger (Q) having a flat surface portion on the projection surface, the flat surface portion having a substantially constant height of the flow path of the first fluid,

the second heat exchange body adjacent to the downstream side of the most upstream heat exchange body located at the most upstream of the flow path of the second fluid is constituted by the heat exchange body (Q).

Drawings

Fig. 1 is a partially cut-away perspective view schematically showing a heat source unit including a heat exchanger according to an embodiment of the present invention.

Fig. 2 is a schematic partially exploded perspective view showing a heat exchanger according to an embodiment of the present invention.

Fig. 3 is a schematic diagram illustrating flows of the first fluid and the second fluid in the heat exchanger according to the embodiment of the present invention.

Fig. 4 is a schematic partially exploded perspective view showing a heat exchanger according to an embodiment of the present invention.

Fig. 5 is a schematic plan view showing an example of the upper surface of one heat exchange plate constituting the heat exchange body (P) having the fluctuating portion in the heat exchanger according to the embodiment of the present invention.

Fig. 6 is a schematic plan view showing an example of the upper surface of another heat exchange plate constituting the heat exchange body (P) having the fluctuating portion in the heat exchanger according to the embodiment of the present invention.

Fig. 7 is a schematic exploded perspective view showing the most upstream heat exchanger and the second heat exchanger in the heat exchanger according to the embodiment of the present invention.

Fig. 8 is a schematic plan view showing an example of the upper surface of one heat exchange plate constituting the heat exchange element (Q) having a flat surface portion in the heat exchanger according to the embodiment of the present invention.

Fig. 9 is a schematic plan view showing an example of the upper surface of another heat exchange plate constituting the heat exchange body (Q) having a flat surface portion in the heat exchanger according to the embodiment of the present invention.

Fig. 10 is a schematic partial sectional view showing a heat exchanger according to an embodiment of the present invention.

Detailed Description

Hereinafter, a plate heat exchanger according to the present embodiment and a heat source device including the plate heat exchanger will be described in detail with reference to the drawings.

As shown in fig. 1, the heat source unit according to the present embodiment is a hot water heater that heats water (first fluid) flowing from an inflow pipe 20 into a heat exchanger 1 by combustion exhaust gas (second fluid) generated by a burner 31 and supplies the heated water to a hot water user (not shown) such as a faucet or a shower through an outflow pipe 21. Although not shown, the water heater is assembled within the housing. Further, another heat medium (for example, antifreeze) may be used as the first fluid.

In this water heater, the burner body 3, the combustion chamber 2, the heat exchanger 1, and the drain receiver 40, which constitute the outer shell of the burner 31, are arranged in this order from above. A fan case 4 is disposed on one side (right side in fig. 1) of the burner body 3, and the fan case 4 includes a combustion fan that sends a mixed gas of fuel gas and air into the burner body 3. Further, an exhaust duct 41 communicating with the drain receiving portion 40 is disposed on the other side (left side in fig. 1) of the burner body 3. The exhaust duct 41 discharges the combustion exhaust gas discharged to the drain receiver 40 to the outside of the water heater.

In the present description, when the water heater is viewed in a state in which the fan case 4 and the exhaust duct 41 are respectively disposed on the sides of the burner body 3, the depth direction corresponds to the front-rear direction, the width direction corresponds to the left-right direction, and the height direction corresponds to the up-down direction.

The burner body 3 has a substantially elliptical shape in plan view, and is formed of, for example, stainless steel. Although not shown, the burner body 3 is open downward.

A gas introduction portion communicating with the fan housing 4 protrudes upward from a central portion of the burner main body 3. The burner body 3 includes a planar burner 31 having a downward combustion surface 30. By operating the combustion fan, the air-fuel mixture is supplied into the burner main body 3.

The burner 31 is of an all-primary-air combustion type, and is composed of, for example, a ceramic combustion plate having a plurality of flame holes (not shown) that open downward, or a combustion mat in which metal fibers are woven into a net shape. The mixed gas supplied into the burner main body 3 is discharged downward from the downward combustion surface 30 by the supply air pressure of the combustion fan. By igniting the mixture gas, a flame is formed on the combustion surface 30 of the burner 31, and combustion exhaust gas is generated. Therefore, the combustion exhaust gas discharged from the combustor 31 is sent to the heat exchanger 1 via the combustion chamber 2. Then, the combustion exhaust gas passing through the heat exchanger 1 is discharged to the outside of the water heater through the drain receiving portion 40 and the exhaust pipe 41.

That is, in the heat exchanger 1, the upper side on which the burner 31 is provided corresponds to the upstream side of the gas flow path of the combustion exhaust gas, and the lower side opposite to the side on which the burner 31 is provided corresponds to the downstream side of the gas flow path of the combustion exhaust gas.

The combustion chamber 2 has a substantially elliptical shape in plan view. The combustion chamber 2 is formed of, for example, stainless steel metal. The combustion chamber 2 is formed by bending a substantially rectangular metal plate so as to be open in the vertical direction and joining both end portions.

As shown in fig. 2, the heat exchanger 1 has a substantially elliptical shape in plan view. The heat exchanger 1 is a plate heat exchanger in which a plurality of (here, thirteen) thin plate-like heat exchange bodies 10 are stacked (laminated). The heat exchanger 1 may have a case covering the periphery thereof.

As shown in fig. 2 to 4, the heat exchanger 1 is configured by stacking a plurality of (here, four stages of) blocks 5 having one or more heat exchange bodies 10 in the vertical direction. Hereinafter, when these blocks 5 are collectively referred to, they are simply referred to as "blocks 5". The uppermost stage block 5 is referred to as an "uppermost stream block 5 a", the intermediate stage block 5 is referred to as a "first downstream side block 5 b" and a "second downstream side block 5 c" in this order from the upstream side, and the lowermost stage block 5 is referred to as a "lowermost stream block 5 d" along the gas flow path of the combustion exhaust gas. The most upstream block 5a and the first downstream block 5b are each constituted by one heat exchange body 10. The second downstream block 5c is formed by stacking five heat exchange elements 10, and the most downstream block 5d is formed by stacking six heat exchange elements 10. The heat exchanger 1 may be constituted by three or less or five or more blocks 5. As will be described later, when one block 5 is constituted by a plurality of heat exchange elements 10, water flows in parallel in the same direction inside each of the heat exchange elements 10 constituting the one block 5. The adjacent heat exchange elements 10 in each block 5 communicate with each other so that water flows upward from below. The adjacent blocks 10 communicate with each other so that water flows upward from below. The adjacent blocks 5 are configured such that the flow direction of water flowing through the inside of each heat exchanger 10 in one block 5 is opposite to the flow direction of water flowing through the inside of each heat exchanger 10 in the other block 5. Therefore, the heat exchanger 1 has four flow paths (four passages) corresponding to the number of stages of the blocks 5, and the flow path of water in each block 5 is folded back between the adjacent blocks 5. This forms a long flow path for water in the heat exchanger 1, and can improve thermal efficiency.

Next, the structure of the heat exchanger 10 will be described. As shown in fig. 2 to 9, the basic configuration such as the size and shape of each heat exchange element 10 is common. However, the heat exchange element 10 of the second downstream block 5c and the most downstream block 5d is different from the heat exchange element 10 of the most upstream block 5a and the first downstream block 5b in the shape of a through hole, the presence or absence of a fluctuation portion, and the like, which will be described later. Hereinafter, the heat exchanger 10 will be referred to as "heat exchanger 10" in short. In addition, when the second downstream-side block 5c and the most downstream-side block 5d are collectively configured as a heat exchange body 10 having a fluctuating portion described later, they are simply referred to as "heat exchange body (P)", and when the most upstream-side block 5a and the first downstream-side block 5b are collectively configured as a heat exchange body 10 having a flat portion described later, they are simply referred to as "heat exchange body (Q)". Therefore, the structure of the heat exchange body (P) will be described first, and the structure of the heat exchange body (Q) different from that of the heat exchange body (P) will be mainly described. The drawings do not necessarily show actual dimensions, and do not limit the embodiments.

Each of the heat exchange bodies (P) of the second downstream block 5c and the most downstream block 5d is formed by overlapping a pair of upper heat exchange plates 11 and lower heat exchange plates 12 having a common structure in the vertical direction and joining predetermined portions to be described later by joining means such as brazing filler metal, except for the positions of the upper and lower through holes, the presence or absence of water passage holes at the corners, and the like, which are partially different in structure. As shown in fig. 4 to 6, the upper and lower

heat exchange plates

11, 12 of the heat exchange body (P) have a substantially elliptical shape in plan view. The upper and lower

heat exchange plates

11 and 12 are formed of, for example, a stainless steel metal plate having a predetermined thickness. The upper and lower

heat exchange plates

11, 12 each have: a plurality of substantially circular upper and lower through

holes

11a, 12a formed over substantially the entire surface of the plate except for the corners; and upper and lower through-

hole flange portions

11c, 12c formed at the peripheral edges of the upper and lower through-

holes

11a, 12 a. The upper and lower through

holes

11a and 12a may have other shapes such as a substantially elliptical shape or a substantially rectangular shape.

Upper and lower peripheral edge joint portions W1, W2 protruding upward are formed on the peripheral edges of the upper and lower

heat exchange plates

11, 12, respectively. The lower peripheral edge engagement portion W2 of the lower heat exchange plate 12 is set as follows: when the lower peripheral edge joining portion W2 is joined to the lower peripheral edge of the upper heat exchange plate 11, the upper heat exchange plate 11 and the lower heat exchange plate 12 are separated from each other with a gap of a predetermined height.

In addition, the upper peripheral edge joint portion W1 of the upper heat exchange plate 11 is set as follows: when the upper peripheral edge joining portion W1 is joined to the lower peripheral edge of the lower heat exchange plate 12 of the adjacent upper heat exchange body (P), the upper heat exchange plate 11 of the lower heat exchange body (P) is separated from the lower heat exchange plate 12 of the adjacent upper heat exchange body (P) by a gap of a predetermined height.

Therefore, the lower peripheral edge joining portion W2 of the lower heat exchange plate 12 is joined to the lower peripheral edge of the upper heat exchange plate 11, thereby forming an internal space 14 (see fig. 3) having a predetermined height. Further, by joining the plurality of heat exchange bodies (P), an exhaust space 15 (see fig. 3) having a predetermined height is formed between the vertically adjacent heat exchange bodies (P).

The upper and lower through

holes

11a and 12a of the heat exchanger body (P) are provided in a grid pattern at predetermined intervals in the front-rear and right-left directions over substantially the entire surfaces of the upper and lower

heat exchange plates

11 and 12 excluding four corners. The upper and lower through-

hole flange portions

11c, 12c extend substantially horizontally outward in the circumferential direction from the opening edges of the upper and lower through-

holes

11a, 12a, and have an outer shape having a substantially octagonal shape in plan view. In the present embodiment, the upper and lower through

holes

11a and 12a have the same size and shape. However, if the pair of upper and lower through

holes

11a, 12a facing each other in the up-down direction are formed in the same size and shape, the other pair of upper and lower through

holes

11a, 12a may be different in size and shape.

The upper and lower through

holes

11a, 12a and the upper and lower through

hole flange portions

11c, 12c are formed at positions corresponding to each other when the upper and lower

heat exchange plates

11, 12 are stacked. The upper and lower through-

holes

11a, 12a and the upper and lower through-

hole flanges

11c, 12c are formed on the bottom surface of the inwardly protruding step portion by drawing so that the facing upper and lower through-

hole flanges

11c, 12c come into surface contact when the upper and lower

heat exchange plates

11, 12 are stacked.

Therefore, when the upper and lower through-

hole flange portions

11c and 12c are joined by joining means such as brazing filler metal in a state where the upper and lower

heat exchange plates

11 and 12 are superposed on each other, the upper and lower through-

hole flange portions

11c and 12c form a flange portion 16 (see fig. 10) that closes the internal space 14. Further, the upper and lower through

holes

11a and 12a form a through hole 13 penetrating the internal space 14 in a non-communicating state.

Substantially circular upper and

lower recesses

11b, 12b are formed between the four upper and lower through

holes

11a, 12a adjacent in the front-rear and left-right directions, respectively. In addition, in the peripheral regions of the upper and lower

heat exchange plates

11 and 12, upper and

lower recesses

11b and 12b having a substantially elliptical shape in plan view are formed between two upper and lower through

holes

11a and 12a adjacent in the front-rear or right-left direction. Further, substantially central portions of the vertical recessed

portions

11b and 12b are formed with vertical projecting

portions

11d and 12d having a smaller diameter than the vertical recessed

portions

11b and 12 b. These upper and lower

concave portions

11b, 12b and upper and lower

convex portions

11d, 12d are formed at positions corresponding to each other when the upper and lower

heat exchange plates

11, 12 are superposed. Therefore, the upper and lower

concave portions

11b, 12b and the upper and lower

convex portions

11d, 12d are formed in a grid pattern at predetermined intervals in the front-rear and right-left directions over substantially the entire surfaces of the upper and lower

heat exchange plates

11, 12 excluding the four corners. The intervals in the front-rear and left-right directions between the adjacent upper and lower

concave portions

11b, 12b are set to be substantially the same as the intervals between the adjacent upper and lower through

holes

11a, 12a, respectively. Therefore, the upper and lower through

holes

11a, 12a and the upper and lower

concave portions

11b, 12b are alternately formed at substantially equal intervals in the front-rear and left-right directions. The upper and lower

concave portions

11b, 12b are formed substantially in the center of the regions surrounded by the four upper and lower through

holes

11a, 12a adjacent to each other in the front-rear and left-right directions, excluding the peripheral edge regions of the upper and lower

heat exchange plates

11, 12. The upper and lower

concave portions

11b, 12b have diameters smaller than the shortest distance between two upper and lower through-

hole flange portions

11c, 12c adjacent in the front-rear and left-right directions.

The upper and lower

concave portions

11b and 12b are formed by a drawing process so as to protrude toward the inside of the internal space 14 by a predetermined height when the upper and lower

heat exchange plates

11 and 12 are stacked. The inward projecting height of the upper and lower

concave portions

11b, 12b is set lower than the projecting height of the upper and lower through-

hole flange portions

11c, 12 c. The upper and lower

convex portions

11d and 12d are formed by drawing so as to protrude outward of the internal space 14 by a predetermined height when the upper and lower

heat exchange plates

11 and 12 are stacked. The outward projection heights of the upper and lower

convex portions

11d, 12d are set lower than the projection heights of the upper and lower peripheral edge joining portions W1, W2, respectively. Therefore, when the upper and lower

heat exchange plates

11, 12 are superposed, the upper and lower

concave portions

11b, 12b form a varying portion 17 for reducing the height of the internal space 14, and a narrow internal space 14 (see fig. 10) having a predetermined height is formed between the upper and lower

concave portions

11b, 12 b. Further, the upper and lower

convex portions

11d and 12d formed at substantially central portions of the upper and lower

concave portions

11b and 12b form a varying portion 18 for increasing the height of the internal space 14, and a wide internal space 14 having a predetermined height is formed between the upper and lower

convex portions

11d and 12d (see fig. 10). Although not shown, a flow path for water is formed between the variable portion 17 and the adjacent flange portion 16. The upper and lower

concave portions

11b, 12b and the upper and lower

convex portions

11d, 12d may have other shapes such as a substantially elliptical shape or a substantially rectangular shape. Moreover, only one of the

variable portions

17 and 18 may be formed.

The upper and lower

heat exchange plates

11, 12 of the heat exchange body (P) each have a water passage hole 63 at least one corner portion. A water passage hole flange portion that extends substantially horizontally outward in the circumferential direction from the opening edge of the water passage hole 63 is formed on the periphery of the water passage hole 63. The water passage holes 63 provided at least one corner of the upper and lower

heat exchange plates

11, 12 forming one heat exchange body (P) are opened to communicate with the internal space 14 formed between the upper and lower

heat exchange plates

11, 12 when the upper and lower

heat exchange plates

11, 12 are overlapped.

As shown in fig. 2 to 3 and 7 to 9, the heat exchanger (Q) has: the shapes of the upper and lower through

holes

11a, 12a and the upper and lower through

hole flange parts

11c, 12c are different from those of the heat exchange body P; no upper and lower concave portions and no upper and lower convex portions are formed in the region surrounded by the four upper and lower through

holes

11a, 12a adjacent in the front-rear and left-right directions; in the peripheral regions of the upper and lower

heat exchange plates

11, 12, upper and lower concave portions are not formed between two upper and lower through

holes

11a, 12a adjacent in the front-rear or left-right direction; and the upper heat exchange plate 11 forming the heat exchange body (Q) at the most upstream has the same structure as the heat exchange body (P) except that no water passage holes are formed. The heat exchange bodies (Q) of the uppermost stream block 5a and the first downstream block 5b are formed by overlapping a pair of upper heat exchange plates 11 and lower heat exchange plates 12 having a common structure in the vertical direction and joining predetermined portions by joining means such as brazing filler metal, except for the positions of the upper and lower through

holes

11a and 11b and the presence or absence of the water passage holes 63 at the corners. Therefore, the upper and lower

heat exchange plates

11 and 12 constituting the heat exchange body (Q) are joined to each other, thereby forming an internal space 14 (see fig. 3) having a predetermined height. Further, by joining the plurality of heat exchange bodies (Q), an exhaust space 15 (see fig. 3) having a predetermined height is formed between the vertically adjacent heat exchange bodies (Q). Further, by joining the heat exchange body (P) and the heat exchange body (Q), an exhaust space 15 (see fig. 3) having a predetermined height is formed between the vertically adjacent heat exchange body (P) and the heat exchange body (Q).

The upper and lower

heat exchange plates

11, 12 of the heat exchange body (Q) each have a plurality of substantially square upper and lower through

holes

11a, 12a formed substantially over the entire surface of the plate except for the corners and the peripheral edge region. Further, substantially square upper and lower through-

hole flange portions

11c, 12c are formed at the peripheral edges of the substantially square upper and lower through-

holes

11a, 12 a. A plurality of substantially pentagonal upper and lower through

holes

11a, 12a are formed in the peripheral edge regions of the upper and lower

heat exchange plates

11, 12. Further, substantially pentagonal upper and lower through-

hole flange portions

11c, 12c are formed at the peripheral edges of the substantially pentagonal upper and lower through-

holes

11a, 12 a. The upper and lower through

holes

11a and 12a may have other shapes such as a substantially circular shape or a substantially elliptical shape. These upper and lower through

holes

11a, 12a and upper and lower through

hole flange portions

11c, 12c are formed at substantially the same pitch as the heat exchange body (P). Therefore, when the upper and lower

heat exchange plates

11, 12 are joined, a substantially square flange portion 16 that closes the substantially square through hole 13 and the internal space 14 is formed in the region of the heat exchange body (Q) other than the peripheral edge region. In addition, a substantially pentagonal flange 16 that closes the substantially pentagonal through hole 13 and the internal space 14 is formed in the peripheral edge region of the heat exchange element (Q). In addition, unlike the heat exchange body (P), no uneven portion is formed in the region surrounded on four sides by the through hole 13. Therefore, the heat exchanger (Q) has a flat surface portion 19 in which the height of the internal space 14 is substantially constant between the four through holes 13 adjacent in the front-rear and left-right directions.

The through-holes 13 of the heat exchange body (Q) in the regions other than the peripheral edge region are arranged as follows: the four apexes are directed toward the front, rear, left, and right peripheral edges of the heat exchanger (Q), and one side of the through hole 13 is substantially parallel to one side of the through hole 13 adjacent in the oblique direction. Therefore, the through-hole 13 is arranged as follows: each apex projects toward a region surrounded by the adjacent four through holes 13 as viewed from the direction of the gas flow path of the combustion exhaust gas. In addition, the flange portion 16 is formed as follows: four apexes (for example, apexes on the right side) of the flange portion 16 are located closer to the center of the through hole 13 adjacent in the oblique direction than apexes on the opposite side (for example, apexes on the left side) of the flange portion 16 adjacent in the oblique direction. That is, when viewed from the front-rear direction and the left-right direction of the heat exchanger Q, one flange portion is disposed so as to partially overlap a flange portion adjacent in the oblique direction.

The water passage holes 63 provided at least one corner of the upper and lower

heat exchange plates

11, 12 forming each heat exchange body (Q) are opened so as to communicate with the internal space 14 formed between the upper and lower

heat exchange plates

11, 12 when the upper and lower

heat exchange plates

11, 12 are overlapped.

As shown in fig. 3, the through holes 13 of the heat exchangers (P), (Q) are each arranged as follows: the through holes 13 of one heat exchanger 10 and the through holes 13 of the other heat exchanger 10 of the adjacent heat exchangers 10 are shifted in the left-right direction perpendicular to the gas flow path direction of the combustion exhaust gas. That is, the heat exchangers 10 adjacent to each other in the up-down direction are arranged so that the projection plane of the through hole 13 of one heat exchanger 10 does not overlap the through hole 13 of the other heat exchanger 10. Therefore, the combustion exhaust gas flowing from the upstream side flows out to the exhaust space 15 between one heat exchange body 10 and the heat exchange body 10 adjacent on the downstream side after passing through the through holes 13 of the heat exchange body 10. The combustion exhaust gas flowing out to the exhaust space 15 collides with the upper heat exchange plates 11 of the heat exchange bodies 10 adjacent on the downstream side, and flows further downstream from the through holes 13 of the heat exchange bodies 10 adjacent on the downstream side. That is, when the combustion exhaust gas flows from the upstream side to the downstream side in the heat exchanger 1, a zigzag-shaped gas flow path is formed in the heat exchanger 1. This increases the contact time between the combustion exhaust gas in the heat exchanger 1 and the upper and lower

heat exchange plates

11 and 12. The

variable portions

17 and 18 of the heat exchanger (P) and the flat surface portion 19 of the heat exchanger (Q) are disposed on the projection surface 55 of the through hole 13 of the adjacent heat exchanger 10 (see fig. 10). The relationship between the through-hole 13 of the heat exchanger (P) and the through-hole 13 of the heat exchanger (Q) is also the same as described above (see fig. 3 and 10).

Next, the flow of the combustion exhaust gas and the water in the heat exchanger 1 will be described with reference to fig. 3. Each block 5 has an inlet 71 for introducing water into the block 5 and an outlet 72 for discharging water to the outside of the block 5. The introduction port 71 and the discharge port 72 are respectively constituted by predetermined water passage holes 63 of the heat exchange element 10 positioned at the most downstream and the most upstream of the gas flow path of the combustion exhaust gas of each block 5. In order to avoid complication, the flange portion 16 and the concave-convex portion around the through hole 13 are omitted in fig. 3.

The inflow pipe 20 is connected to a water passage hole 63 formed in a corner portion of the lower heat exchange plate 12 located on the right front side of the heat exchange body (P) located on the most downstream side of the gas flow path of the combustion exhaust gas (hereinafter referred to as "the most downstream heat exchange body 10 s"). Further, a lead-out pipe 23 extending upward from the downstream-most heat exchange body 10s to a heat exchange body (Q) located at the most upstream of the gas flow path of the combustion exhaust gas (hereinafter referred to as "the upstream-most heat exchange body 10 a") is inserted into a water passage hole 63 forming a corner portion on the right-side rear side of the lower heat exchange plate 12 of the downstream-most heat exchange body 10 s. The upper end of the delivery pipe 23 is connected to a water passage hole 63 forming a right rear corner of the lower heat exchange plate 12 of the most upstream heat exchange body 10 a. The outer peripheral surface of the delivery pipe 23 is joined to the inner peripheral edge of the water passage hole 63 forming the right rear corner of the lower heat exchange plate 12 of the most downstream heat exchange body 10s by joining means such as brazing filler metal. The upper end opening of the delivery pipe 23 communicates with the internal space 14 of the upstream-most heat exchanger 10 a. When the delivery pipe 23 is inserted from the most downstream heat exchanger 10s to the most upstream heat exchanger 10a, the delivery pipe 23 penetrates the internal space 14 of the heat exchanger 10 other than the most upstream heat exchanger 10a and all the exhaust spaces 15 between the adjacent heat exchangers 10 in a non-communicating state.

Therefore, the water flowing into the internal space 14 of each heat exchange body (P) of the most downstream block 5d from the water passage hole 63 at the right front corner flows in one of the left and right directions (from the right to the left in fig. 3) in the internal space 14. The water flowing into the internal space 14 of each heat exchange body (P) of the second downstream block 5c from the water passage holes 63 at the left front and rear corners flows in one of the left and right directions (from the left to the right in fig. 3) in the internal space 14. The flow path direction of water flowing through the internal space 14 of the heat exchange body (P) of the second downstream block 5c is opposite to that of the most downstream block 5 d. The water flowing into the internal space 14 of the heat exchange element (Q) (hereinafter referred to as "second heat exchange element 10 b") of the first downstream block 5b from the water passage hole 63 at the right front corner flows in one of the left and right directions (from the right to the left in fig. 3) in the internal space 14. The flow path direction of the water flowing through the internal space 14 of the second heat exchanger 10b is opposite to that of the second downstream block 5 c. The water flowing into the internal space 14 of the upstream-most heat exchange element 10a from the water passage holes 63 at the left front and rear corners flows in one of the left-right directions (from the left to the right in fig. 3) in the internal space 14. The flow path direction of the water flowing through the internal space 14 of the most upstream heat exchanger 10a is opposite to that of the second heat exchanger 10 b. The water flowing through the internal space 14 of the upstream-most heat exchanger 10a flows out to the outlet pipe 23 connected to the water flow hole 63 at the right rear corner of the upstream-most heat exchanger 10 a. The water flowing out of the delivery pipe 23 flows down through the delivery pipe 23 and flows out of the heat exchanger 1 through the outflow pipe 21 connected to the most downstream heat exchanger 10 s. In this way, the most upstream heat exchanger 10a and the second heat exchanger 10b in the upstream region of the gas flow path of the combustion exhaust gas are connected in series so that all the water flowing into the second heat exchanger 10b flows into the most upstream heat exchanger 10 a. The plurality of heat exchange bodies (P) of the most downstream block 5d are connected in parallel to form a plurality of parallel flow paths. The second downstream block 5c also has the same structure as the most downstream block 5 d.

Next, with reference to fig. 10, the flow of the combustion exhaust gas in the upstream region of the gas flow path of the combustion exhaust gas and the flow of water in the internal space 14 of the heat exchange bodies (P) and (Q) will be described. Fig. 10 is a partial cross-sectional view of the heat exchanger (P) and (Q) in a direction inclined at a predetermined angle with respect to the front-rear direction and the left-right direction of the heat exchanger (P) and (Q), respectively, to clarify the difference between the heat exchangers (P) and (Q).

The water flows between the water passage holes 63 separated in the left-right direction of the heat exchange bodies (P) and (Q). The heat exchanger (P) has fluctuating portions (17, 18) for increasing and decreasing the height of the water flow path in the region surrounded by the through-hole (13). Therefore, when water flowing from the upstream side in the internal space 14 passes through the inside of the fluctuating

portions

17 and 18, the flow resistance of the water increases, and the flow rate of the water decreases. When water passes through the inside of the fluctuating

portions

17 and 18, turbulent flow of water is generated, and the temperature distribution of water is reduced. Furthermore, the surface area of the heat exchange body (P) is increased by the fluctuating

portions

17 and 18, and therefore the heat receiving area of the heat exchange body (P) is increased. This enables the heat received from the combustion exhaust gas to be efficiently transferred to the water on the downstream side of the gas flow path of the combustion exhaust gas. Furthermore, by laminating a heat exchange body (P) having excellent heat transfer properties on the downstream side of the heat exchange body (Q), sensible heat of high-temperature combustion exhaust gas can be absorbed by the heat exchange body (Q) on the upstream side, and latent heat of combustion exhaust gas can be absorbed by the heat exchange body (P) on the downstream side. This can improve the thermal efficiency.

On the other hand, in the present embodiment, the combustion exhaust gas flows in the vertical direction through the through holes 13 of the heat exchange bodies 10. Therefore, the through-holes 13 of each heat exchange body 10 are formed as follows: the combustion exhaust gas flows outside the heat exchange bodies 10 in a direction substantially perpendicular to the flow path surface of the water flowing inside each heat exchange body 10. The through holes 13 are formed at substantially constant intervals in the front-rear and left-right directions over substantially the entire surface of each heat exchanger 10. Therefore, the combustion exhaust gas flowing from the upstream side of the gas flow path collides with the entire surface of the upstream-most heat exchange element 10a except for the through holes 13, and heats the upstream-most heat exchange element 10 a. That is, in the most upstream heat exchanger 10a, the portion other than the through-hole 13 becomes a heat receiving surface. On the other hand, as described above, the adjacent heat exchange bodies 10 are formed such that the projection surfaces 55 of the through holes 13 of one heat exchange body 10 do not overlap the through holes 13 of the other heat exchange body 10. Therefore, the combustion exhaust gas flowing through the through-holes 13 of the most upstream heat exchanger 10a first intensively collides with the small-area projection surface 55 on the second heat exchanger 10 b. The combustion exhaust gas that collides with the second heat exchanger 10b also includes high-temperature combustion exhaust gas that does not come into contact with the most upstream heat exchanger 10a (i.e., combustion exhaust gas that does not exchange heat with water flowing through the internal space 14 of the most upstream heat exchanger 10 a). Therefore, when the heat exchanger 1 is configured only by the heat exchanger (P) having the

conversion portions

17 and 18, local overheating is likely to occur in the second heat exchanger 10b adjacent to the downstream side of the most upstream heat exchanger 10 a.

However, according to the present embodiment, the second heat exchanger 10b is constituted by the heat exchanger (Q) having the flat surface portion 19 having a substantially constant height of the flow path of water. The flat surface portion 19 is formed on a projection surface 55 of the through hole 13 of the uppermost heat exchange element 10a, which is a region surrounded on four sides by the through hole 13 (see fig. 7 to 10). Therefore, the flow path resistance of the water flowing inside the projection surface 55 of the heat exchanger (Q) is smaller than the flow path resistance of the water flowing inside the projection surface 55 of the heat exchanger (P), and the flow rate of the water flowing inside the projection surface 55 of the heat exchanger (Q) increases. Further, since the flat surface portion 19 is not formed with irregularities, the combustion exhaust gas colliding with the flat surface portion 19 is uniformly diffused in all directions. As a result, the concentration of heat on the projection surface 55 on which the combustion exhaust gas intensively collides can be alleviated. Thereby, local overheating of the second heat exchange body 10b can be prevented.

The combustion exhaust gas having the highest temperature collides with the most upstream heat exchanger 10a, and the peripheral edge portion of the through hole 13 through which the combustion exhaust gas passes is heated most. Therefore, if the flow rate of water is small, local overheating may occur in the most upstream heat exchanger 10 a. However, according to the present embodiment, the most upstream heat exchange body 10a is constituted by the heat exchange body (Q). Therefore, the four-sided region surrounded by the through-holes 13 in the most upstream heat exchanger 10a, i.e., the projection surface 55 of the through-hole 13 of the second heat exchanger 10b has the flat surface portion 19. This can prevent local overheating of the most upstream heat exchanger 10 a.

In addition, according to the present embodiment, the most upstream heat exchanger 10a and the second heat exchanger 10b in the upstream region of the gas flow path of the combustion exhaust gas are connected in series such that water flows through the second heat exchanger 10b and the most upstream heat exchanger 10a in this order. Therefore, all the water flowing through the second heat exchange element 10b flows into the most upstream heat exchange element 10 a. Therefore, even in the case where the amount of water supplied into the heat exchanger 1 is small, local overheating in the second heat exchanger 10b and the most upstream heat exchanger 10a can be prevented.

In addition, according to the present embodiment, the through-holes 13 of the most upstream heat exchanger 10a and the second heat exchanger 10b have a substantially square shape. Further, the substantially square through holes 13 are arranged such that each vertex protrudes toward a region surrounded by the adjacent substantially square through holes 13, that is, the projection plane 55, when viewed from the direction of the gas flow path of the combustion exhaust gas. Therefore, the flow velocity of water flowing through the region surrounded by the substantially square through-hole 13 becomes high. This can further prevent local overheating.

In the present embodiment, the heat exchange body (Q) constituting the most upstream heat exchange body 10a and the second heat exchange body 10b has a convex portion protruding outward between the adjacent through holes 13 in the peripheral edge region of the heat exchange body (Q). The projection surface 55 is also formed in these peripheral edge regions, but the through-hole 13 is not formed on the peripheral edge portion side of the projection surface 55. On the other hand, through holes 13 are formed in four directions on a projection surface 55 of the heat exchanger body (Q) except for the projection surface 55 of the peripheral edge region. Therefore, the projection surface 55 surrounded on four sides by the through holes 13 receives more heat from the combustion exhaust gas than the projection surface 55 in the peripheral edge region, and local overheating is likely to occur. Therefore, if the flat surface portion 19 is formed on at least the projection surface 55 of the heat exchanger element (Q) except the projection surface 55 of the peripheral edge region, local overheating can be effectively prevented. Further, by forming the uneven portions between the adjacent through holes 13 in the peripheral edge region of the heat exchange body (Q), the heat of the combustion exhaust gas can be efficiently transferred to the water.

As described above, according to the present embodiment, the heat efficiency can be improved, and the local heating of the heat exchange body 10 in the upstream area of the gas flow path of the combustion exhaust gas can be prevented. Therefore, according to the present embodiment, a plate heat exchanger having high thermal efficiency and excellent durability can be provided.

(other embodiments)

(1) In the above embodiment, the heat exchange body on the downstream side of the second heat exchange body is constituted only by the heat exchange body (P) having the conversion portion. However, when local overheating occurs also in the heat exchanger downstream of the second heat exchanger, the heat exchanger (Q) may be used instead of a part of the heat exchanger (P). In addition, the uppermost heat exchange element may be a heat exchange element (P) instead of the heat exchange element (Q).

(2) In the above embodiment, the burner having the downward combustion surface is disposed above the heat exchanger. However, a burner having an upward combustion surface may be disposed below the heat exchanger.

(3) In the above embodiment, a plurality of heat exchange bodies are stacked up and down. However, a plurality of heat exchange bodies may be stacked left and right.

(4) In the above embodiment, the water heater is used, but a heat source machine such as a boiler may be used.

The present invention has been described in detail above, but the present invention is summarized as follows.

According to the present invention, there is provided a plate heat exchanger including a plurality of heat exchange bodies that exchange heat between a first fluid flowing inside and a second fluid flowing outside, the plate heat exchanger being configured by stacking the plurality of heat exchange bodies,

the plurality of heat exchangers includes: a heat exchange body (P) having a varying portion, which has a varying portion in which the height of the flow path of the first fluid varies on the projection surface; and a heat exchanger (Q) having a flat surface portion, which has a flat surface portion on the projection surface, the height of the flow path of the first fluid being substantially constant,

at least the second heat exchange body adjacent to the downstream side of the most upstream heat exchange body positioned at the most upstream of the flow path of the second fluid is constituted by the heat exchange body (Q).

According to the heat exchanger, the heat exchange body (P) has a varying portion in which the height of the flow path of the first fluid varies on the projection surface of the through hole of the adjacent heat exchange body. Therefore, the flow path resistance of the first fluid is increased by the varying portion, and the flow rate of the first fluid flowing through the inside of the projection surface is decreased. In addition, when the first fluid passes through the inside of the projection surface, turbulence of the first fluid is generated, and therefore, the temperature distribution of the first fluid can be reduced. In addition, the surface area of the heat exchange body (P) is increased by the fluctuating portion, and therefore the heat receiving area of the heat exchange body (P) is increased. This enables the heat received from the second fluid to be efficiently transferred to the first fluid.

On the other hand, in the upstream area of the flow path of the second fluid, the high-temperature second fluid that has passed through the through-hole of the most upstream heat exchange body intensively collides with the small-area projection surface of the second heat exchange body. When the variable portion is formed on the projection surface as described above, the flow rate of the first fluid flowing through the inside of the projection surface is likely to decrease. Therefore, if all the heat exchangers are constituted by the heat exchanger (P) having the conversion portion, local overheating is likely to occur on the projection surface on which the through hole of the most upstream heat exchanger is projected onto the second heat exchanger. However, according to the above heat exchanger, the second heat exchanger is constituted by the heat exchanger (Q) having the flat surface portion in which the height of the flow path of the first fluid is substantially constant on the projection surface of the through hole of the adjacent heat exchanger. Therefore, the flow path resistance of the first fluid flowing inside the projection surface of the heat exchanger (Q) is smaller than that when the first fluid passes through the projection surface of the heat exchanger (P), and the flow rate of the first fluid flowing inside the projection surface of the heat exchanger (Q) is increased. In addition, since the irregularities are not formed on the flat surface portion, the second fluid colliding with the flat surface portion is uniformly diffused in four directions. This can alleviate the concentration of heat on the projection surface of the second heat exchanger.

Preferably, in the above-described heat exchanger,

the heat exchange body at the most upstream is composed of the heat exchange body (Q) having the flat surface portion.

According to the heat exchanger, local overheating of the heat exchange body on the most upstream side, which the high-temperature second fluid collides with, can be prevented.

Preferably, in the above-described heat exchanger,

the planar portion is formed on the projection surface of the heat exchange body (Q) having the planar portion except at least a peripheral edge region.

In the case where the projection surface of the through hole of one heat exchanger is formed in the peripheral edge region of the other heat exchanger, the through hole is not formed at least on the peripheral edge portion side of the projection surface. On the other hand, through holes are formed in four directions on a projection plane of a region of the heat exchanger other than the peripheral region. Therefore, the amount of heat received from the second fluid in the projection plane surrounded on four sides by the through hole is larger than that in the projection plane of the peripheral region. As a result, local overheating is likely to occur on the projection surface of the heat exchange body in the upstream region of the flow path of the second fluid in the region other than the peripheral region. Therefore, if a flat surface portion is formed on the projection surface of the heat exchanger (Q) at least in the region other than the peripheral region, local overheating can be effectively prevented.

Preferably, in the above-described heat exchanger,

the second heat exchange fluid and the most upstream heat exchange fluid are connected in series such that the first fluid flows sequentially inside the second heat exchange fluid and the most upstream heat exchange fluid.

According to the above heat exchanger, all of the first fluid flowing through the second heat exchange element flows through the most upstream heat exchange element. Thus, even when the flow rate of the first fluid supplied to the heat exchanger is small, local overheating of the most upstream heat exchanger and the second heat exchanger can be effectively prevented.

Preferably, in the above-described heat exchanger,

the through-hole of the heat exchange body (Q) having the planar portion has a substantially rectangular shape,

the substantially rectangular through hole is disposed such that at least one apex thereof protrudes toward the projection surface.

According to the heat exchanger, the flow velocity of the first fluid flowing through the projection surface is increased. This can further prevent local overheating.

Claims

1. A plate heat exchanger, characterized in that,

the plate heat exchanger is provided with a plurality of heat exchange bodies which exchange heat between a first fluid flowing inside and a second fluid flowing outside, and is configured by stacking the plurality of heat exchange bodies,

2. A plate heat exchanger according to claim 1,

the most upstream heat exchange body is constituted by the heat exchange body (Q).

3. A plate heat exchanger according to claim 1,

the planar portion is formed on the projection surface of a region of the heat exchange body (Q) other than the peripheral region.

4. A plate heat exchanger according to any one of claims 1-3,

the second heat exchange fluid and the most upstream heat exchange fluid are connected in series such that the first fluid flows sequentially through the second heat exchange fluid and the most upstream heat exchange fluid.

5. A plate heat exchanger according to claim 1,

the through-hole of the heat exchange body (Q) has a substantially rectangular shape,